Table 1.
Baseline characteristics of the study population.
| Characteristics | All patients | Training sample | Validation sample | P value |
|---|---|---|---|---|
| Number | 411 | 288 | 123 | |
| Gender, N (%) | 0.492 | |||
| male | 230 (56.0%) | 158 (54.9%) | 72 (58.5%) | |
| female | 181 (44.0%) | 130 (45.1%) | 51 (41.5%) | |
| Age, mean ± SD | 58.4 ± 10.6 | 58.8 ± 10.2 | 57.4 ± 11.4 | 0.239 |
| Type of tumor, N (%) | 0.667 | |||
| rapid | 191 (46.5%) | 138 (47.9%) | 53 (43.1%) | |
| moderate | 164 (39.9%) | 112 (38.9%) | 52 (42.3%) | |
| slow | 56 (13.6%) | 38 (13.2%) | 18 (14.6%) | |
| Tumor location, N (%) | 0.906 | |||
| cervical | 49 (11.9%) | 33 (11.5%) | 16 (13.0%) | |
| thoracic | 206 (50.1%) | 145 (50.3%) | 61 (49.6%) | |
| lumbar | 156 (38.0%) | 110 (38.2%) | 46 (37.4%) | |
| Number of spinal metastases, N (%) | 0.356 | |||
| single | 161 (39.2%) | 117 (40.6%) | 44 (35.8%) | |
| multiple | 250 (60.8%) | 171 (59.4%) | 79 (64.2%) | |
| BMI (kg/m2), N (%) | 0.991 | |||
| < 18.5 | 13 (3.2%) | 9 (3.1%) | 4 (3.3%) | |
| 18.5-30 | 349 (84.9%) | 245 (85.1%) | 104 (84.6%) | |
| > 30 | 49 (11.9%) | 34 (11.8%) | 15 (12.2%) | |
| Surgical procedure, N (%) | 0.351 | |||
| type 1 | 68 (16.5%) | 43 (14.9%) | 25 (20.3%) | |
| type 2 | 319 (77.6%) | 229 (79.5%) | 90 (73.2%) | |
| type 3 | 24 (5.8%) | 16 (5.6%) | 8 (6.5%) | |
| Preoperative radiotherapy, N (%) | 0.426 | |||
| yes | 246 (59.9%) | 176 (61.1%) | 70 (56.9%) | |
| no | 165 (40.1%) | 112 (38.9%) | 53 (43.1%) | |
| Preoperative chemotherapy, N (%) | 0.441 | |||
| yes | 239 (58.2%) | 171 (59.4%) | 68 (55.3%) | |
| no | 172 (41.8%) | 117 (40.6%) | 55 (44.7%) | |
| Visceral metastases, N (%) | 0.462 | |||
| no | 100 (24.3%) | 73 (25.3%) | 27 (22.0%) | |
| yes | 311 (75.7%) | 215 (74.7%) | 96 (78.0%) | |
| Blood loss (liters), mean ± SD | 1.3 ± 1.1 | 1.2 ± 0.9 | 1.3 ± 1.3 | 0.497 |
| Preoperative Frankel score, N (%) | 0.693 | |||
| A-C | 109 (26.5%) | 78 (27.1%) | 31 (25.2%) | |
| D-E | 302 (73.5%) | 210 (72.9%) | 92 (74.8%) | |
| Blood transfusion, N (%) | 0.194 | |||
| yes | 177 (43.1%) | 130 (45.1%) | 47 (38.2%) | |
| no | 234 (56.9%) | 158 (54.9%) | 76 (61.8%) | |
| Charlson comorbidity index, N (%) | 0.131 | |||
| 6 | 63 (15.3%) | 42 (14.6%) | 21 (17.1%) | |
| 7 | 117 (28.5%) | 75 (26.0%) | 42 (34.1%) | |
| ≥8 | 231 (56.2%) | 171 (59.4%) | 60 (48.8%) | |
| Operative time (hours), mean ± SD | 4.0 ± 1.4 | 4.0 ± 1.3 | 4.1 ± 1.6 | 0.759 |